1. Field of the Invention
This invention relates generally to devices and methods for measuring physical performance and more particularly to a device that assesses the complex grip capability/capacity of a human hand.
2. Background
Strength testing of the injured hand and forearm is of immense interest to injured patients, treating physicians, therapists, and insurance providers. The Jamar Hand Dynamometer, (herein “the Jamar”), has been the standard clinical strength-testing device of injured and diseased hands for over 40 years.
The Jamar is used to measure grip force by means of grasping two offset parallel bars that can be situated at one of five preset positions to accommodate various hand sizes. The subject is asked to squeeze the offset parallel bars of the device and the highest force exerted is measured and displayed on a mechanical gage. The Jamar is essentially isometric in use and allows almost no perceptible motion of the handles. The Jamar has survived in the face of criticism for inaccuracy, questionable reliability, and lack of meaningful clinical relevance. The handles of the Jamar are parallel offset bars that represent a very limited number of tasks found in activities of daily living. The Jamar is of little use when evaluating the function of a finger or fingers and offers little meaningful information regarding grip analysis. It is believed by some that the Jamar survives because of cost, ease of use, availability, and lack of a suitable replacement.
Medical examinations performed by physicians and therapists rely upon the Jamar to evaluate the functional capacity and disability of the hand, evaluations which directly affect employment and injury award compensation. In addition to the aforementioned limitations, the Jamar is vulnerable to fraudulent efforts on behalf of the subject. Malingering manipulation and falsification at the will of the examinee are an ever-present concern with significant financial ramifications. Patient effort is best surmised through a series of testing methods that distract the subject during testing, however the results of such methods are suspected to yield unacceptable levels of false positives.
Alternative hand strength testing devices have been designed, tested, and marketed but have failed to gain acceptance. Such testing devices based upon pneumatic and spring mechanisms have been trialed, but have been criticized for inaccuracy, poor reliability, and lack of meaningful clinical relevance. In addition, like the Jamar, specific analysis about individual finger function in the context of the function of entire hand cannot be acquired. Finally, like the Jamar, insight into patient effort can be only surmised through a series of testing methods, which distract the subject during testing. Because these devices were found to be no better and in some manners worse than the Jamar, broad acceptance for implementation of non-hydraulic dynamometers has failed to occur.
Accordingly, there is a need for an improved grip assessment tool that can measure the complex grip capability/capacity of a human hand without the constraints and design drawbacks observed in the prior art. Additionally, advantage may be found in providing a device, method and system for the assessment of grip force that provides analysis and output relating to individual finger function in the context of the function of entire hand.
Therefore one object of the present invention is to provide a device, method and system for the assessment of grip force that provides analysis and output including a display of grip force data representative of individual finger function in the context of the function of entire hand. A further objective of the present invention is to provide a device, method and system for the assessment of grip force that can collect, condition, analyze and output data and imagery representative of a complex grip capability/capacity of a human hand including the palm and all digits. Yet another objective of the present invention is to provide a device, method and system for the assessment of grip force that can provide a grip force map image that presents a detailed rendering of the complex grip capability/capacity of a human hand including the palm and all digits that will provide an improvement over existing assessment systems and their attendant inaccuracy, poor reliability, and lack of meaningful clinical relevance.